[R] aggregate() example fails

[Kenneth Roy Cabrera Torres]

Hi R users and developers.

I compile the 
R version 2.8.1 Patched (2009-03-18 r48193)
On my UBUNTU linux distribution.

But hen I ask for the aggregate example it fails.

What am I missing?

example(aggregate)

aggrgt> ## Compute the averages for the variables in 'state.x77',
grouped
aggrgt> ## according to the region (Northeast, South, North Central,
West) that
aggrgt> ## each state belongs to.
aggrgt> aggregate(state.x77, list(Region = state.region), mean)
Error en FUN(X[[1L]], ...) : 
  elemento 1 esta vacio;
  la parte de la lista de argumentos  'is.list' ha sido evaluada:
   (INDEX)

I discovery this behavior when I try to use old scripts that uses
the aggregate() function, but now it fails on my old scripts.

Thank you for your help.

Kenneth 
PD: R.Version() returns:
$platform
[1] "x86_64-unknown-linux-gnu"
$arch
[1] "x86_64"
$os
[1] "linux-gnu"
$syste
[1] "x86_64, linux-gnu"
$status
[1] "Patched"
$major
[1] "2"
$minor
[1] "8.1"
$year
[1] "2009"
$month
[1] "03"
$day
[1] "18"
$`svn rev`
[1] "48193"
$language
[1] "R"
$version.string
[1] "R version 2.8.1 Patched (2009-03-18 r48193)"